Tools
Variance & Risk of Ruin
How much your results can swing, how confident you can be in your winrate, and the odds a downswing breaks your bankroll.
—Risk of ruin at this bankroll
—Chance you're a long-term winner
Over this sample
- Expected result
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- One standard deviation
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- Likely winrate (95%)
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Risk of ruin uses the standard formula e^(−2·winrate·bankroll ÷ variance) and assumes a fixed winrate. Heads-up std. deviation typically runs ~100–130 bb/100. A confidence interval this wide is why six-figure samples still don't settle a winrate.
Frequently asked
- What is risk of ruin in poker?
- Risk of ruin is the probability your bankroll reaches zero before variance turns around. It falls quickly as your bankroll or winrate rises and as your standard deviation drops.
- How big a sample do I need to trust my winrate?
- Larger than most expect. With a 110 bb/100 standard deviation, even 100,000 hands leaves a wide confidence interval — the tool shows the exact 95% range for your sample.
- What standard deviation should I use?
- Heads-up no-limit usually runs about 100–130 bb/100, higher than full-ring because you play every hand. Use your tracker's figure if you have one.
- Is the variance calculator free?
- Yes. It is free with no signup, and the risk-of-ruin and confidence figures are exact closed-form results.